DEPARTMENT  OF  THE  INTERIOR 

JOHN  BARTON  PAYNE.  SECRETARY 

NATIONAL  PARK  SERVICE 

STEPHEN  T.  MATHER.  DIRECTOR 


EOLOGICAL  HISTORY 
yf  THE  YELLOWSTONE 
NATIONAL  PARK 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1920 


THE  NATIONAL  PARKS  AT  A  GLANCE. 

[Number,  19;  total  area,  10,859  square  miles.] 


National  parks  in 
order  of  creation. 

Location. 

Area  in 
square 
miles. 

Distinctive  characteristics. 

Hot  Springs 

Middle  Arkansas 

H 

1S32 
Yellowstone 

Northwestern     Wyo- 

3,348 

Many  hotels  and  boarding  houses—  20  bath- 
houses under  public  control. 

More  geysers  than  in  all  rest  of  world  together  — 

1872 
Sequoia 

ming. 
Middle  eastern   Cali- 

252 

Boiling  springs—  Mud  volcanoes—  Petrified  for- 
ests —  Grand  Canyon  of  the  Yellowstone,  re- 
markable for  gorgeous  coloring  —  Large  lakes  — 
Many  large  streams  and  waterfalls—  Vast  wil- 
derness, greatest  wild  bird  and  animal  preserve 
in  world  —  Exceptional  trout  fishing. 

The  Big  Tree  National  Park    12  000  sequoia  trees 

1890 
Yosemite  

fornia. 
Middle  eastern   Cali- 

1,125 

over  10  feet  in  diameter,  some  25  to  36  feet  in 
diameter—  Towering   mountain  ranges—  Start- 
ling precipices  —  Cave  of  considerable  size. 

Valley  of  world-famed  beautv  —  Lofty  cliffs  —  Ro- 

1890 
General  Grant  

fornia. 

Middle  eastern   Cali- 

4 

mantic    vistas  —  Many    waterfalls   of  extraor- 
dinary height—  3   groves  of   big  trees—  High 
Sierra—  Waterwheel  falls—  Good  trout  fishing. 

Created  to  preserve  the  celebrated  General  Grant 

1890 
Mount  Rainier 

fornia. 
West  central   Wash- 

324 

Tree,  35  feet  in  diameter—  6  miles  from  Sequoia 
National  Park. 

Largest  accessible  single  peak  glacier  system  —  28 

1899 
Crater  Lake 

ington. 
Southwestern  Oregon 

249 

glaciers,  some  of  large  size  —  48  square  miles  of 
glacier,  50  to  500  feet  thick—  Wonderful  sub- 
alpine  wild  flower  fields. 

Lake  of  extraordinary  blue  in  crater  of  extinct 

1902 
Wind  Cave 

South  Dakota 

17 

volcano—  Sides  1,000  feet  high—  Interesting  lava 
formations  —  Fine  fishing. 

Cavern   having   many   miles   of  galleries   and 

1903 
Platt... 

Southern  Oklahoma 

numerous  chambers  containing  peculiar  forma- 
tions. 

Many   sulphur   and    other   springs    possessing 

1904 
Sullys  Hill 

North  Dakota 

u 

medicinal  value. 
Small  park  with  woods,  streams,  and  a  lake  —  Is 

1904 
Mesa  Verde 

Southwestern      Colo- 

77 

an  important  wild-animal  preserve. 
Most  notable  and  best  preserved  prehistoric  cliff 

1906 
Glacier 

rado. 
Northwestern     Mon- 

1 534 

dwellings  in  United  States,  if  not  in  the  world. 
Rugged  mountain  region  of  unsurpassed  Alpine 

1910 

Rocky  Mountain.  .  . 
1915 

Hawaii. 

tana. 

North    middle    Colo- 
rado. 

Hawaii  

397J 

118 

character  —  250    glacier-fed    lakes  of  romantic 
beauty—  60    small    glaciers—  Precipices    thou- 
sands of  feet  deep—  Almost  sensational  scenery 
of  marked  individuality  —  Fine  trout  fishing. 

Heart  of  the  Rockies—  Snowy  range,  peaks  11,000 
to  14,250  feet  altitude  —  Remarkable  records  of 
glacial  period. 

Three  separate  areas  —  Kilauea  and  Mauna  Loa 

1916 

Lassen  Volcanic... 
1916 

Mount  McKinley  .  .  . 
1917 

Grand  Canyon  
1919 

Lafayette.. 

Northern  California.  .  . 
South  central  Alaska.. 

North  central  Arizona. 
Maine  coast  

124 
2,200 

958 

8 

on  Hawaii,  Haleakala  on  Maui. 

Only  active  volcano  in  United  States  proper  — 
Lassen   Peak   10,465  feet—  Cinder  Cone  6,870 
feet  —  Hot  springs  —  Mud  geysers. 

Highest    mountain   in    North    America—  Rises 
higher  above  surrounding  country  than  any 
other  mountain  in  the  world. 

The  greatest  example  of  erosion  and  the  most 
sublime  spectacle  in  the  world. 

The  group  of  granite  mountains  upon  Mount 

1919 
Zion... 

Southwestern  Utah.  .  . 

120 

Desert  Island. 
Magnificent  gorge  (Zion  Canyon)  depth  frum  800 

1919 

to  2,000  feet,  with  precipitous  walls—  Of  great 
beauty  and  scenic  interest. 

Bancroft  Li 


GEOLOGICAL  HISTORY  OF  THE  YELLOWSTONE 
NATIONAL  PARK. 


By  ARNOLD  HAGUE, 

United  States  Geological  Survey. 


The  purpose  of  this  paper  is  not  so  much  to  elucidate  any  special 
problem  connected  with  the  many  interesting  geological  questions  to 
be  found  in  the  Yellowstone  Park,  as  to  offer  such  a  general  view  of 
the  region  as  will  enable  the  tourist  to  understand  clearly  something  of 
its  physical  geography  and  geology. 

The  Yellowstone  Park  is  situated  in  the  extreme  northwestern  portion 
of  Wyoming.  At  the  time  of  the  enactment  of  the  law  establishing  this 
national  reservation  the  region  had  been  little  explored,  and  its  relation 
to  the  physical  features  of  the  adjacent  country  was  little  understood. 
Since  that  time  surveys  have  shown  that  only  a  narrow  strip  about  2 
miles  in  width  is  situated  in  Montana  and  that  a  still  narrower  strip 
extends  westward  into  Idaho. 

The  area  of  the  park  as  at  present  defined  is  somewhat  more  than 
3,300  square  miles. 

The  Central  Plateau,  with  the  adjacent  mountains,  presents  a  sharply 
defined  region,  in  strong  contrast  with  the  rest  of  the  northern  Rocky 
Mountains.  It  stands  out  boldly,  is  unique  in  topographical  structure, 
and  complete  as  a  geological  problem. 

The  central  portion  of  the  Yellowstone  Park  is  essentially  a  broad, 
elevated,  volcanic  plateau,  between  7,000  and  8,500  feet  above  sea  level, 
and  with  an  average  elevation  of  about  8,000  feet.  Surrounding  it  on 
the  south,  east,  north,  and  northwest  are  mountain  ranges  with  culmi- 
nating peaks  and  ridges  rising  from  2,000  to  4,000  feet  above  the  general 
level  of  the  inclosed  table-land. 

For  present  purposes  it  is  needless  to  confine  ourselves  strictly  to  legal 
boundaries,  but  rather  to  consider  the  entire  region  in  its  broader  physical 
features. 

South  of  the  park  the  Tetons  stand  out  prominently  above  the  sur- 
rounding country,  the  highest,  grandest  peaks  in  the  northern  Rocky 
Mountains.  The  eastern  face  of  this  mountain  mass  rises  with  unri- 
valled boldness  for  nearly  7,000  feet  above  Jackson  Lake.  Northward 

3 


4  GEOLOGICAL   HISTORY   OF   YELLOWSTONE   PARK. 

the  ridges  fall  away  abruptly  beneath  the  lavas  of  the  park,  only  the 
outlying  spurs  coming  within  the  limits  of  the  reservation.  For  the 
most  part  the  mountains  are  made  up  of  coarse  crystalline  gneisses  and 
schists,  probably  of  Archean  age,  flanked  on  the  northern  spurs  by 
upturned  Paleozoic  strata.  To  the  east  of  the  Tetons,  across  the  broad 
valley  of  the  Upper  Snake,  generally  known  as  Jackson  Hole,  lies  the 
well-known  Wind  River  Range,  famous  from  the  earliest  days  of  the 
Rocky  Mountain  trappers.  The  northern  end  of  this  range  is  largely 
composed  of  Mesozoic  strata,  single  ridges  of  Cretaceous  sandstone  pene- 
trating still  farther  northward  into  the  regions  of  the  park  and  protruding 
above  the  great  flows  of  lava. 


THE  ABSAROKA  RANGE  ALONG  THE  EASTERN  EDGE  OF  THE  PARK. 

Along  the  entire  eastern  side  of  the  park  stretches  the  Absaroka 
Range — so  called  from  the  Indian  name  of  the  Crow  Nation.  The  Absa- 
roka Range  is  intimately  connected  with  the  Wind  River  Range,  the  two 
being  so  closely  related  that  any  line  of  separation  must  be  drawn  more 
or  less  arbitrarily,  based  more  upon  geological  structures  and  forms  of 
erosion  than  upon  physical  limitations. 

The  Absarokas  offer  for  more  than  80  miles  a  bold,  unbroken  barrier; 
a  rough,  rugged  country,  dominated  by  high  peaks  and  crags  from  10,000 
to  11,000  feet  in  height.  The  early  trappers  found  it  a  forbidding  land; 
prospectors  who  followed  them,  a  barren  one. 

At  the  northeast  corner  of  the  park  a  confused  mass  of  mountains  con- 
nects the  Absarokas  with  the  Snowy  Range.  This  Snowy  Range  shuts 
in  the  park  on  the  north  and  is  an  equally  rough  region  of  country,  with 


GEOLOGICAL   HISTORY   OF   YELLOWSTONE   PARK.  5 

elevated  mountain  masses  covered  \\ith  snow  the  greater  part  of  the 
year,  as  tin-  name  would  indicate.  Only  the  southern  slopes,  which  rim 
in  tlu-  park  region,  come  within  the  limit  of  our  investigation.  Here  the 
rocks  arc  mainly  granites,  gneisses,  and  schists,  the  sedimentary  beds, 
for  the  most  part,  referable  to  the  pre-Cambrian  series. 

The  Gallatin  Range  incloses  the  park  on  the  north  and  northwest. 
It  lies  directly  west  of  the  Snowy,  only  separated  by  the  broad  valley 
of  the  Yellowstone  River.  It  is  a  range  of  great  beauty,  of  diversified 
forms,  and  varied  geological  problems.  Electric  IVak,  in  the  northwest- 
ern corner  of  the  park,  is  the  culminating  point  in  the  range,  and  affords 
one  of  the  most  extended  views  to  be  found  in  this  part  of  the  country. 


II IK  GALLATIN  RANGE  IN  THE  NORTHEASTERN  PORTION   OF 

THE   PARK. 

Archean  gneisses  form  a  prominent  mass  in  the  range,  over  which  occur 
;  ies  of  sandstones,  limestones,  and  shales,  of  Paleozoic  and  Mesozoic 
age,  representing  Cambrian,  Silurian,  Devonian,  Carboniferous,  Trias, 
Jura,  and  Cretaceous.  Immediately  associated  with  these  sedimentary 
beds,  are  large  masses  of  intrusive  rocks,  which  have-  played  an  impor- 
tant part  in  bringing  about  the  present  structural  features  of  the  range. 
They  are  all  of  the  andesitic  type,  but  show  considerable  range  in 
mineral  composition,  including  pyroxene,  hornblende,  and  hornblende- 
mica  varieties.  These  intrusive  masses  are  found  in  narrow  dikes,  in 
immense  interbedded  sheets  forced  between  the  different  strata,  and  as 
laccolites,  a  mode  of  occurrence  first  described  from  the  Henry  Mountains 
in  Utah,  by  Mr.  G.  K.  Gilbert,  but  now  well  recognized  elsewhere  in  the 
northern  Cordillera. 


6  GEOLOGICAL  HISTORY   OF   YELLOWSTONE   PARK. 

We  see  then  that  the  Absarokas  rise  as  a  formidable  barrier  on  the  east- 
ern side  of  the  park,  the  Gallatins  as  a  steep  mural  face  on  the  west  side, 
while  the  other  ranges  terminate  abruptly,  rimming  in  the  park  on  the 
north  and  south,  and  leaving  a  depressed  region  not  unlike  the  parks  of 
Colorado,  only  covering  a  more  extended  area  with  a  relatively  deeper 
basin.  The  region  has  been  one  of  profound  dynamic  action,  and  the 
center  of  mountain  building  on  a  grand  scale. 

It  is  not  my  purpose  at  the  present  time  to  enter  upon  the  details  of 
geological  structure  of  these  ranges,  each  offering  its  own  special  study 
and  field  of  investigation.  My  desire  is  simply  to  call  attention  to  their 
general  features  and  mutual  relations.  So  far  as  their  age  is  concerned, 
evidence  goes  to  show  that  the  action  of  upheaval  was  contemporaneous 
in  all  of  them,  and  coincident  with  the  powerful  dynamic  movements 
which  uplifted  the  north  and  south  ranges,  stretching  across  Colorado, 
Wyoming,  and  Montana.  This  dynamic  movement  blocked  out,  for 
the  most  part,  the  Rocky  Mountains,  near  the  close  of  the  Cretaceous, 
although  there  is  good  reason  to  believe  that  in  this  region  profound 
faulting  and  displacement  continued  the  work  of  mountain  building  well 
into  the  Middle  Tertiary  period. 

Throughout  Tertiary  time  in  the  park  area,  geological  history  was  char- 
acterized by  great  volcanic  activity,  enormous  volumes  of  erupted  mate- 
rial being  poured  out  in  the  Eocene  and  Middle  Tertiary,  continuing  with 
less  force  through  the  Pliocene,  and  extending  into  Quaternary  time. 
Within  very  recent  times  there  is  no  evidence  of  any  considerable  out- 
burst; indeed  the  region  may  be  considered  long  since  extinct.  These 
volcanic  rocks  present  a  wide  range  in  chemical  and  mineral  composi- 
tion and  physical  structure.  They  may  all,  however,  be  classed  under 
three  great  groups — andesites  with  basalts,  rhyolites,  and  basalts — fol- 
lowing each  other  in  the  order  named.  In  general,  the  relative  age 
of  each  group  is  clearly  and  sharply  defined,  the  distribution  and  mode 
of  occurrence  of  each  presenting  characteristics  and  salient  features  fre- 
quently marked  by  periods  of  erosion. 

Andesites  are  the  only  volcanic  rocks  which  have  played  an  important 
part  in  producing  the  present  structural  features  of  the  mountains  sur- 
rounding the  park.  As  already  mentioned,  they  occur  in  large  masses  in 
the  Gallatin  Range,  while  most  of  the  culminating  peaks  in  the  Absarokas 
are  composed  of  compact  andesites  and  andesitic  breccias.  On  the  other 
hand,  the  andesites  are  not  confined  to  the  mountains,  but  played  an 
active  role  in  filling  up  the  interior  basin.  That  the  duration  of  the 
andesitic  eruptions  was  long  continued  is  made  evident  by  the  plant 
remains  found  in  ash  and  lava  beds  through  2,000  feet  of  volcanic 
material. 

In  early  Tertiary  times,  a  volcano  burst  forth  in  the  northeast  corner 
of  this  depressed  area  not  far  from  the  junction  of  the  Absaroka  and 
Snowy  Ranges.  While  not  to  be  compared  in  size  and  grandeur  with  the 


GEOLOGICAL  HISTORY  OF  YELLOWSTONE  PARK.  7 

volcanoes  of  California  and  the  Cascade  Range,  it  is,  for  the  Rocky 
Mountains,  one  of  no  mean  proportions.  It  rises  from  a  base  about 
6,500  feet  above  sea  level,  the  culminating  peak  attaining  an  elevation  of 
10,000  feet.  This  gives  a  height  to  the  volcano  of  3,5<x>  iVrt  from  base- 
to  summit,  measuring  from  the  Archean  rocks  of  the  Yellowstone  Valley 
to  the  top  of  Mount  Washburn.  The  average  height  of  the  crater  rim  is 
about  9,000  feet  above  sea  level,  the  volcano  measuring  15  miles  across 
the  base.  The  eruptive  origin  of  Mount  Washburn  has  long  been  recog- 
nized, and  it  is  frequently  referred  to  as  a  volcano.  It  is  however  simply 
the  highest  peak  among  several  others,  and  represents  a  later  outburst 
which  destroyed  in  a  measure  the  original  rim  and  form  of  an  older 
crater.  The  eruptions  for  the  most  part  were  basic  andesites.  Erosion 
has  so  worn  away  the  earlier  rocks,  and  enormous  masses  of  more  recent 
lavas  have  so  obscured  the  original  form  of  lava  flows,  that  it  is  not  easy 
for  an  inexperienced  eye  to  recognize  a  volcano  and  the  surrounding  peaks 
as  the  more  elevated  points  in  a  grand  crater  wall.  By  following  around 
on  the  ancient  andesitic  rim,  and  studying  the  outline  of  the  old  crater, 
together  with  the  composition  of  its  lavas,  its  true  origin  and  history  may 
readily  be  made  out.  It  has  been  named  the  Sherman  volcano.  This 
old  volcano  of  early  Tertiary  time  occupies  a  prominent  place  in  the 
geological  development  of  the  park,  and  dates  back  to  the  earliest  out- 
bursts of  lava  which  have  in  this  region  changed  a  depressed  basin  into 
an  elevated  plateau.  We  have  here  a  volcano  situated  far  inland,  in  an 
elevated  region,  in  the  heart  of  the  Rocky  Mountains.  It  lies  on  the 
eastern  side  of  the  continent,  only  a  few  miles  from  the  great  Continental 
Divide,  which  sends  its  waters  to  both  the  Atlantic  and  Pacific. 

After  the  dying  out  of  the  andesitic  and  basaltic  lavas,  followed  by  a 
period  of  erosion,  immense  volumes  of  rhyolite  were  erupted,  which  not 
only  threatened  to  fill  the  crater  but  to  bury  the  outer  walls  of  the  vol- 
cano itself.  On  all  sides  the  andesitic  slopes  were  submerged  beneath  the 
rhyolite  to  a  height  of  from  8,000  to  8,500  feet.  This  enormous  mass  of 
rhyolite,  poured  out  after  the  close  of  the  andesitic  period,  did  more  than 
anything  else  to  bring  about  the  present  physical  features  of  the  park  table- 
land. A  tourist  visiting  all  the  prominent  geyser  basins,  hot  springs,  Yel- 
lowstone Lake,  and  the  Grand  Canyon  and  Falls  of  the  Yellowstone,  is  not 
likilv  to  come  upon  any  other  rock  than  rhyolite,  excepting,  of  course, 
deposits  from  the  hot  springs,  unless  he  ascends  Mount  Washbuni,  A 
description  of  the  rhyolite  region  is  essentially  one  of  the  Central  Plateau. 
Taking  the  bottom  of  the  basin  at  6,500  feet  above  sea  level,  these  acidic 
lavas  were  piled  up  until  the  accumulated  mass  measured  2,000  fee  t  in 
thickness.  It  completely  encircled  the  Gallatin  Range,  burying  its  lower 
slopes  on  both  the  east  and  west  sides;  it  banked  up  all  along  the  \YI-M 
flanks  of  the  Absarokas,  and  buried  the  outlying  spurs  of  the  Teton  and 
the  Wind  River  Plateaus. 


8  GEOLOGICAL  HISTORY   OF  YELLOWSTONE   PARK. 

The  Central  Plateau  covers  an  area  approximately  50  by  40  miles,  with 
a  mean  altitude  of  8,000  feet.  It  is  accidented  by  undulating  basins  of 
varied  outline  and  scored  by  deep  canyons  and  gorges.  Strictly  speak- 
ing, it  is  not  a  plateau ;  at  least  it  is  by  no  means  a  level  area,  but  a  rugged 
country,  characterized  by  bold  escarpments  and  abrupt  edges  of  mesa- 
like  ridges.  But  few  large  vents  or  centers  of  volcanic  activity  for  the 
rhyolite  have  been  recognized,  the  two  principal  sources  being  the  vol- 
cano to  which  reference  has  already  been  made  and  Mount  Sheridan  in 
the  southern  end  of  the  park.  Mount  Sheridan  is  the  most  commanding 
peak  on  the  plateau,  with  an  elevation  10,385  feet  above  sea  level  and 
2,600  feet  above  Heart  Lake.  From  the  summit  of  the  peak  on  a  clear 
day  one  may  overlook  the  entire  plateau  country  and  the  mountains 
which  shut  it  in,  while  almost  at  the  base  of  the  peak  lie  the  magnificent 
lakes  which  add  so  much  to  the  quiet  beauty  of  the  region,  in  contrast 
to  the  rugged  scenery  of  the  mountains.  From  no  point  is  the  magni- 
tude and  grandeur  of  the  volcanic  region  so  impressive.  The  lava  flows — 
bounded  on  the  east  by  the  Absarokas — extend  westward  not  only  across 
the  park,  but  across  the  Madison  Plateau,  and  out  on  to  the  great  plains  of 
Snake  River,  stretching  far  westward  almost  without  a  break  in  the  con- 
tinuity of  eruptive  flows.  Over  the  central  portion  of  the  park,  where 
the  rhyolites  are  thickest,  erosion  has  failed  to  penetrate  to  the  under- 
lying rock.  Even  such  deep  gorges  as  the  Yellowstone,  Gibbon,  and 
Madison  Canyons  have  nowhere  worn  through  these  rhyolite  flows.  In 
the  Grand  Canyon  of  the  Yellowstone  the  andesitic  breccias  are  found 
beneath  the  rhyolites,  but  the  deepest  cuts  fail  to  reveal  the  underlying 
sedimentary  beds.  Although  the  rocks  of  the  plateau  for  the  most  part 
belong  to  one  group  of  acidic  lavas,  they  by  no  means  present  the 
great  uniformity  and  monotony  in  field  appearance  that  might  be  ex- 
pected. These  2.000  square  miles  offer  as  grand  a  field  for  the  study  of 
structural  forms,  development  of  crystallization,  and  mode  of  occur- 
rence of  acidic  lavas  as  can  be  found  anywhere  in  the  world.  They 
vary  from  a  nearly  holocrystalline  rock  to  one  of  pure  volcanic  glass. 
Obsidian,  pumice,  pitchstone,  ash,  breccia,  and  an  endless  development 
of  transition  forms  alternate  with  the  more  compact  lithoidal  lavas 
which  make  i'r>  the  great  mass  of  the  rhyolite,  and  which  in  colors, 
texture,  and  structural  developments  present  an  equally  varied  aspect. 
In  mineral  composition  these  rocks  are  simple  enough.  The  essential 
minerals  are  orthoclase  and  quartz,  with  more  or  less  plagioclase. 
Sanidine  is  the  prevailing  feldspar,  although  in  many  cases  plagioclase 
forms  occur  nearly  as  abundantly  as  orthoclase.  Chemical  analyses, 
whether  we  consider  the  rocks  from  the  crater  of  Mount  Sheridan,  the 
summit  of  the  plateau,  or  the  volcanic  glass  of  the  world-renowned 
Obsidian  Cliff,  present  comparatively  slight  differences  in  ultimate  com- 
position. 


GEOLOGICAL   HISTORY   OF   YELLOWSTONE    PARK.  9 

I  have  dwelt  SOUK  what  in  detail  upon  the  nature  of  these  rocks  for 
two  reasons:  First,  because  of  the  difficulty  met  with  by  the  scientific 
traveler  in  recognizing  the  uniformity  and  simplicity  of  chemical  com- 
position of  the  rhynlite  magma  over  the  entire  plateau,  owing  to  its 
great  diversity  in  superficial  habit;  second,  on  account  of  their  geolog- 
ical importance  in  connection  with  the  unrivaled  display  of  the  gey- 
sers and  hot  springs.  That  the  energy  of  the  steam  and  thermal 
waters  dates  well  back  into  the  period  of  volcanic  action,  there  is  in 
my  opinion  very  little  reason  to  doubt.  As  the  energy  of  this  under- 
ground heat  is  to-day  one  of  the  most  impressive  features  of  the 
country,  I  will  defer  commenting  upon  the  .geysers  and  hot  springs 
until  speaking  of  the  present  condition  of  the  park. 


OBSIDIAN  CLIFF. 

Although  the  rhyolite  eruptions  were  probably  of  long  duration  and 
died  out  slowly,  there  is,  I  think,  evidence  to  show  that  they  occupied 
a  clearly  and  sharply  defined  period  between  the  andesites  and  late  basalt 
eruptions.  Since  the  outpouring  of  this  enormous  mass  of  rhyolite 
and  building  up  of  the  plateau,  the  region  has  undergone  faulting  and 
displacement;  immense  blocks  of  lava  have  been  lifted  bodily,  and  the 
surface  features  of  the  country  have  been  modified.  Following  the  rhy- 
olite came  the  period  of  late  basalt  eruptions,  which,  in  comparison  with 
the  andesite  and  rhyolite  eras,  was,  so  far  as  the  park  was  con- 
cerned, insignificant,  both  as  regards  the  area  covered  by  the  basalt 
and  its  influence  in  modifying  the  physical  aspect  of  the  region.  The 
basalt  occurs  as  thin  sheets  overlying  the  rhyolite  and  in  some 
937°— 20 2 


10  GEOLOGICAL  HISTORY   OF   YELLOWSTONE   PARK. 

instances  as  dikes  cutting  the  more  acidic  rocks.  It  has  broken  out 
near  the  edge  of  the  rhyolite  body  and  occurs  most  frequently  along  the 
Yellowstone  Valley,  along  the  western  foothills  of  the  Gallatin  Range 
and  Madison  Plateau,  and  again  south  of  the  Falls  River  Basin. 

After  the  greater  part  of  the  basalt  had  been  poured  out  came  the 
glacial  ice,  which  widened  and  deepened  the  preexisting  drainage 
channels,  cut  profound  gorges  through  the  rhyolite  lavas  and  modeled 
the  two  volcanoes  into  their  present  form.  Over  the  greater  part  of  the 
Cordillera  of  the  central  and  northern  Rocky  Mountains,  wherever  the 
peaks  attain  a  sufficiently  high  altitude  to  attract  the  moisture-laden 
clouds,  evidences  of  the  former  existence  of  local  glaciers  are  to  be 
found.  In  the  Teton  Efange  several  well-defined  characteristic  glaciers 
still  exist  upon  the  abrupt  slopes  of  Mount  Hay  den  and  Mount  Moran. 
They  are  the  remnants  of  a  much  larger  system  of  glaciers.  The  park 
region  presents  so  broad  a  mass  of  elevated  country  that  the  entire 
plateau  was,  in  glacial  times,  covered  with  a  heavy  capping  of  ice. 
Evidences  of  glacial  action  are  everywhere  to  be  seen. 

Over  the  Absaroka  Range  glaciers  were  forced  down  into  the  Lamar 
and  Yellowstone  Valleys,  thence  westward  over  the  top  of  Mount  Everts 
to  the  Mammoth  Hot  Springs  Basin.  On  the  opposite  side  of  the  park 
the  ice  from  the  summit  of  the  Gallatin  Range  moved  eastward  across 
Swan  Valley  and  passing  over  the  top  of  Terrace  Mountain  joined  the 
ice  field  coming  from  the  east.  The  united  ice  sheet  plowed  its  way 
northward  down  the  valley  of  the  Gardiner  to  the  Lower  Yellowstone, 
where  the  broad  valley  may  be  seen  strewn  with  the  material  trans- 
ported from  both  the  east  and  west  rims  of  the  park. 

Since  the  dying  out  of  the  rhyolite  eruptions  erosion  has  greatly  modi- 
fied the  entire  surface  features  of  the  park.  Some  idea  of  the  extent 
of  this  action  may  be  realized  when  it  is  recalled  that  the  deep  canyons 
of  the  Yellowstone,  Gibbon,  and  Madison  Rivers — canyons  in  the  strictest 
use  of  the  word— have  all  been  carved  out  since  that  time.  To-day 
these  gorges  measure  several  miles  in  length  and  from  i  ,000  to  i  ,500  feet 
in  depth. 

To  the  geologist  one  of  the  most  impressive  objects  on  the  park  pla- 
teau is  a  transported  bowlder  of  granite  which  rests  directly  upon  the 
rhyolite  near  the  brink  of  the  Grand  Canyon,  about  3  miles  below  the 
falls  of  the  Yellowstone.  It  stands  alone  in  the  forest,  a  long  way  from 
the  nearest  glacial  bowlder.  Glacial  detritus  carrying  granitic  material 
may  be  traced  upon  both  sides  of  the  canyon  wall.  This  massive  block, 
although  irregular  in  shape  and  somewhat  pointed  toward  the  top, 
measures  24  feet  in  length  by  20  feet  in  breadth  and  stands  18  feet  above 
the  base.  The  nearest  point  from  which  it  could  have  been  transported 
is  distant  30  or  40  miles.  Coming  upon  it  in  the  solitude  of  the  forest 
with  all  its  strange  surroundings  it  tells  a  most  impressive  story.  In 


GEOLOGICAL  HISTORY   OF   YELLOWSTONE   PARK.  II 

no  place  are  tin  evidences  of  frost  and  fire  brought  so  forcibly  together 
as  in  tlu   Yellowstone  National  Park. 

Since  the  close  of  the  ice  period  no  geological  events  of  any  moment 
have  brought  about  any  changes  in  the  physical  history  of  the  region 
other  than  those  produced  by  the  direct  action  of  steam  and  thermal 
waters.  A  few  insignificant  eruptions  have  probably  occurred,  but  they 
failed  to  modify  the  broad  outlines  of  topographical  structure  and  pre- 
sent but  little  of  general  interest  beyond  the  evidence  of  the  continu- 
ance of  volcanic  action  into  quaternary  times.  Volcanic  activity  in  the 
park  may  be  considered  as  long  since  extinct.  At  all  events  indications 
of  fresh  lava  flows  within  historical  times  are  wholly  wanting.  This 


GLACIAL  BOWLDER  NEAR  GRAND  CANYON. 

is  not  without  ink-rest,  as  evidence  of  underground  heat  may  be  ob- 
served everywhere  throughout  the  park  in  the  waters  of  the  geysers 
and  hot  springs.  All  our  observations  point  in  one  direction  and  lead 
to  the  theory  that  the  cause  of  the  high  temperatures  of  these  waters 
must  be  found  in  the  heated  rocks  below,  and  that  the  origin  of  the 
heat  is  in  some  way  associated  with  the  source  of  volcanic  energy.  It 
by  no  means  follows  that  the  waters  themselves  are  derived  from  any 
deep-seated  source;  on  the  contrary,  investigation  tends  to  show  that 
the  waters  brought  up  by  the  geysers  and  hot  springs  are  mainly  sur- 
face waters  which  have  percolated  downward  a  sufficient  distance  to 
become  heated  by  large  volumes  of  steam  ascending  through  fissures 
and  vents  from  much  greater  depths.  If  this  theory  is  correct  it  is  but 


12  GEOLOGICAL   HISTORY   OF   YELLOWSTONE   PARK. 

fair  to  demand  that  evidence  of  long-continued  action  of  hot  waters 
and  superheated  steam  should  be  apparent  upon  the  rocks  through 
which  they  passed  on  their  way  to  the  surface.  This  is  precisely  what 
one  sees  in  innumerable  places  on  the  Central  Plateau.  Indeed,  the 
decomposition  of  the  lavas  of  the  rhyolite  plateau  has  proceeded,  on  a 
most  gigantic  scale,  and  could  only  have  taken  place  after  the  lapse  of 
an  enormous  period  of  time  and  the  giving  off  of  vast  quantities  of  heat, 
if  we  are  to  judge  at  all  by  what  we  see  going  on  around  us  to-day.  The 
ascending  currents  of  steam  and  hot  water  have  been  powerful  geo- 
logical agents,  and  have  left  an  indelible  impression  upon  the  surface 
of  the  country.  The  most  striking  example  of  this  action  is  found  in 
the  Grand  Canyon  of  the  Yellowstone.  From  the  Lower  Falls  for  3  miles 
down  the  river  abrupt  walls  upon  both  sides  of  the  canyon,  a  thousand 
feet  in  depth,  present  a  brilliancy  and  mingling  of  color  beyond  the 
power  of  description.  From  the  brink  of  the  canyon  to  the  water's 
edge  the  walls  are  sheer  bodies  of  decomposed  rhyolite.  Varied  hues 
of  orange,  red,  purple,  and  sulphur-yellow  are  irregularly  blended  in  one 
confused  mass.  There  is  scarcely  a  piece  of  unaltered  rock  in  place. 
Much  of  it  is  changed  into  kaolin;  but  from  rhyolite,  still  easily  re- 
cognized, occur  transition  products  of  every  possible  kind  to  good  porce- 
lain clay.  This  is  the  result  of  the  long-continued  action  of  steam  and 
vapors  upon  the  rhyolite  lavas.  Through  this  mass  of  decomposed 
rhyolite  the  course  of  ancient  steam  vents  in  their  upward  passage  may 
still  be  traced,  while  at  the  bottom  of  the  canyon  hot  springs,  fumaroles, 
and  steam  vents  are  still  more  or  less  active,  but  probably  with  dimin- 
ished power. 

Still  other  areas  are  quite  as  convincing,  if  not  on  so  grand  a  scale, 
as  the  Yellowstone  Canyon.  Josephs  Coat  Basin,  on  the  east  side  of 
the  canyon,  and  Brimstone  Hills,  on  the  east  side  of  the  Yellowstone 
Lake,  an  extensive  area  on  the  slopes  of  the  Absaroka  Range,  both 
present  evidences  of  the  same  chemical  processes  brought  about  in  the 
same  manner.  It  is  not  too  strong  a  statement  to  make  to  say  that  the 
plateau  on  the  east  side  of  the  Grand  Canyon,  from  Broad  Creek  to 
Pelican  Creek,  is  completely  undermined  by  the  action  of  superheated 
steam  and  alkaline  waters  on  the  rhyolite  lava.  Similar  processes  may 
be  seen  going  on  to-day  in  all  the  geyser  basins.  A  long  period  of  time 
must  have  been  necessary  to  accomplish  these  changes.  The  study  of 
comparatively  fresh  vents  shows  almost  no  change  from  year  to  year, 
although  careful  scrutiny  during  a  period  of  five  years  detects  a  certain 
amount  of  disintegration,  but  infinitely  small  in  comparison  with  the 
great  bodies  of  altered  rock.  This  is  well  shown  in  a  locality  like  the 
Monarch  Geyser  in  the  Norris  Geyser  Basin,  where  the  water  is  thrown 
out  at  regular  intervals  through  a  narrow  fissure  in  the  rock. 

The  Grand  Canyon  of  the  Yellowstone  offers  one  of  the  most  impres- 
sive examples  of  erosion  on  a  grand  scale  within  recent  geological  times. 


GEOLOGICAL  HISTORY  OF  YELLOWSTONE  PARK.  13 

It  is  self-evident  that  the  deep  canyon  must  be  of  much  later  origin  than 
UK-  rock  through  which  it  has  been  worn,  and  it  seems  quite  clear  that 
the  course  and  outlines  of  the  canyon  were  in  great  part  determined  by 
the  easily  eroded  decomposed  material  forming  the  canyon  walls,  and 
this  in  turn  was  brought  about  by  the  slow  processes  just  described. 

The  evidence  of  the  antiquity  of  the  hot  spring  deposits  is,  perhaps, 
shown  in  an  equally  striking  manner  and  by  a  wholly  different  process 
of  geological  reasoning.  Terrace  Mountain  is  an  outlying  ridge  of  the 
rhyolite  plateau  just  west  of  the  Mammoth  Hot  Springs.  It  is  covered 
on  the  summit  with  thick  beds  of  travertine,  among  the  oldest  portions 
of  the  Mammoth  Hot  Springs  deposits.  It  is  the  mode  of  occurrence 
of  these  calcareous  deposits  from  the  hot  waters  which  has  given  the 
name  to  the  mountain.  Lying  upon  the  surface  of  this  travertiqe  on 
the  top  of  the  mountain  are  found  glacial  bowlders  brought  from  the 
summit  of  the  Gallatin  Range,  15  miles  away,  and  transported  on  the 
ice  sheet  across  Swan  Valley  and  deposited  on  the  top  of  the  mountain, 
700  feet  above  the  intervening  valley.  It  offers  the  strongest  possible 
evidence  that  the  travertine  is  older  than  the  glacier  which  has  strewn 
the  country  with  transported  material.  How  much'  travertine  was 
eroded  by  the  ice  is,  of  course,  impossible  to  say,  but  so  friable  a  material 
would  yield  readily  to  glacial  movement. 

Still  another  method  of  arriving  at  the  great  antiquity  of  the  thermal 
energy  and  the  age  of  the  hot  spring  formation  is  by  determining  the 
rate  of  deposition  and  measuring  the  thickness  of  the  accumulated  sinter. 
This  method,  although  the  one  which  would  perhaps  first  suggest  itself, 
is,  in  my  opinion,  by  no  means  as  satisfactory  as  the  geological  reasoning 
already  given.  It  is  unsatisfactory  because  no  uniform  rate  of  deposi- 
tion can  be  ascertained  for  even  a  single  area,  like  the  Upper  Geyser 
Basin,  and  it  is  still  more  difficult  to  arrive  at  any  conclusion  as  to  the 
growth  of  the  sinter  in  the  past.  Moreover,  it  is  quite  possible  that 
heavy  deposits  may  have  suffered  erosion  before  the  present  sinter  was 
laid  down.  It  however  corroborates  other  methods  and  possesses  the 
advantage  of  being  a  direct  way. 

It  may  be  well  to  add  that  there  exists  the  greatest  contrast  between 
the  deposits  of  the  Mammoth  Hot  Springs  and  those  found  upon  the 
plateau.  At  the  Mammoth  Springs  they  are  nearly  pure  travertin*., 
with  only  a  trace  of  silica,  analyses  showing  from  95  to  99  per  cent  of 
calcium  carbonate.  On  the  plateau,  the  deposits  consist  for  the  most 
part  of  siliceous  sinter,  locally  termed  "geyserite."  The  reason  for  the 
difference  is  this:  At  the  Mammoth  Hot  Springs  the  steam,  although 
ascending  from  fissures  in  the  igneous  rock,  comes  in  contact  with  i he- 
waters  found  in  the  Mcsozoic  strata,  which  here  form  the  surface  rocks. 
The  Jura  or  Cretaceous  limestones  have  furnished  the  lime  held  in  solu- 
tion and  precipitated  on  the  surface  as  travertine.  On  the  other  hand, 
the  mineral  constituents  of  the  plateau  waters  are  derived  almost 


GEOLOGICAL  HISTORY  OF  YELLOWSTONE   PARK.  15 

exclusively   from   the   highly   acidic   lavas,   which  carry  but  a  small 
amount  of  lime. 

Deposition  of  sinter  from  the  hot  waters  of  the  geyser  basins  depends 
in  a  great  measure  on  the  amount  of  silica  held  in  solution,  which  varies 
considerably  at  the  different  localities  and  may  have  varied  still  more 
in  past  time.  The  silica,  as  determined  by  analyses,  ranges  from  0.22 
to  0.60  grammes  per  kilogram  of  water,  the  former  being  the  amount 
found  in  the  water  of  the  caldron  of  the  Excelsior  Geyser  and  the  latter 
at  the  Coral  Spring  in  the  Norris  Basin.  Analysis  shows  that  from 
one-fifth  to  one-third  of  the  mineral  matter  held  in  solution  consists  of 
silica,  the  remaining  constituents  being  readily  soluble  salts  carried  off 
by  surface  drainage.  A  few  springs  highly  charged  with  silica,  like  the 
Coral,  deposit  it  on  the  cooling  of  the  waters;  but  such  springs  are 
exceptional.  At  most  springs  and  geysers  it  results  after  evaporation, 
and  not  from  mere  cooling  of  the  water.  It  seems  probable  that  the 
nature  and  amount  of  alkaline  chlorides  and  carbonates  present  influ- 
ence the  separation  of  silica.  Temperature  also  may  in  some  degree 
influence  the  deposition.  My  friend,  Mr.  Elwood  Hofer,  has  called  my 
attention  to  an  observation  of  his  made  in  midwinter,  while  on  one  of 
his  snowshoe  trips  through  the  park.  He  noticed  that  certain  over- 
flow pools  of  spring  water,  upon  being  frozen,  deposited  a  considerable 
amount  of  mineral  matter.  He  has  sent  me  specimens  of  this  material, 
which,  upon  examination,  proved  to  be  identical  with  the  silica  depos- 
ited from  the  Coral  Spring  upon  the  cooling  of  the  water.  Demijohns  of 
geyser  water  which  have  been  standing  for  one  or  two  years  have  failed 
to  precipitate  any  silica.  Quite  recently,  in  experimenting  upon  these 
waters  in  the  laboratory,  it  was  noticed  that  on  reducing  them  nearly 
to  the  freezing  point  no  change  took  place,  but  upon  freezing  the  waters 
there  was  an  abundant  separation  of  free  silica.  The  waters  frozen  in 
this  way  were  collected  from  the  Coral  Spring.  Xorris  I'.asin.  and  the 
Taurus  Geyser,  Shoshone  Basin. 

Again,  there  is  no  doubt  that  the  algous  growths  flourishing  in  the  hot 
waters  of  the  park  favor  the  secretion  of  silica  and  calcic  carbonate  and 
exert  a  potent  influence  in  building  up  both  the  sinter  and  travertine 
deposits  far  greater  than  one  might  at  first  be  led  to  suppose.  These 
processes  of  assimilation  are  steadily  taking  place  without  interruption, 
as  all  algae  act  as  geological  agents.  The  silica  and  lime  brought  to  the 
surface  by  hot  springs  is,  upon  the  death  of  the  algae,  transformed  into 
sinter  and  travertiiu-.  becoming  rock  masses,  which  later  show  scarcrlv 
any  sign  of  their  origin  from  plant  life.  Tourists  are  seldom  aware  that 
the  harmonious  and  brilliant  tints  are  due  to  vegetable  growths. 
<U  -velop  equally  \\vll  in  the  waters  of  all  basins  and  upon  the 

Urnuvs  of  Mammoth  Hot  Springs.     \VaU-r  boils  in  tin-  t'pjx  i   G 
r..«sin  at  198°  F.,  and  rudimentary  organisms  appear  at  about  185°  F., 
although  no  definite  line  can  be  drawn  beyond  which  all  life  ceases. 


i6 


GEOLOGICAL   HISTORY   OF   YELLOWSTONE    PARK. 


These  low  vegetable  organisms  occur  in  nearly  all  pools,  springs,  and 
running  water  upon  the  plateau.  Wherever  boiling  waters  cool  to  the 
latter  temperature  algae  make  their  appearance,  and  with  the  lowering  of 
temperature  on  exposure  to  air  still  more  highly  organized  forms  gradually 
come  in.  It  is  believed  that  at  about  140°  F.  conditions  are  favorable 
for  a  rapid  development  of  numerous  species.  Many  forms  of  algae 
flourish  within  restricted  ranges  of  temperature,  and  the  different  species 
possess  characteristic  colors  and  habits  of  growth  dependent  upon  such 
changes  of  temperature.  After  a  little  experience  it  is  quite  possible, 
upon  noting  the  nature  of  the  plant  life,  to  make  a  sure  guess  as  to  the 
temperature  of  the  water  in  which  the  species  grow.  As  water  in  the 
geyser  pools  and  caldrons  frequently  stands  at  or  near  the  boiling  point, 
no  life  exists  at  the  centers  of  discharge,  but  with  a  rapid  lowering  of 


ALGAE  BASINS. 

temperature  algae  appear,  with  corresponding  changes  of  color,  in  the 
shallow  pools  and  overflow  channels.  In  the  geyser  basins  the  first 
evidence  of  vegetation  in  an  overflow  stream  consists  of  creamy  white 
filamentary  threads,  passing  into  light  flesh  tints,  then  to  deep  salmon. 
With  distance  from  the  source  of  heat  the  prevailing  colors  pass  from 
bright  orange  to  yellow,  yellowish  green,  and  emerald,  and  in  the  still 
cooler  waters  various  shades  of  brown.  This,  of  course,  is  a  simple  stats- 
ment  of  phenomena  which  really  display  highly  complex  conditions. 
No  two  pools  or  overflow  channels  are  quite  alike  in  their  occurrence 
either  as  regards  flow  of  water  or  development  of  algae. 

Several  methods  have  been  devised  for  ascertaining  the  growth  of 
deposition  of  the  geyserite.  One  way  is  by  allowing  the  water  to  trickle 
over  twigs,  dried  grasses,  or  almost  anything  exposing  considerable 


GEOLOGICAL   HISTORY   OF   YELLOWSTONE   PARK.  I/ 

surface,  and  noting  the  amount  of  incrustation.  This  way  gives  the  most 
rapid  results,  but  is  far  from  satisfactory  and  by  no  means  reproduces 
the  conditions  existing  in  nature.  Other  methods  employed  are  placing 
objects  on  the  surface  of  the  water  or,  still  better,  partially  submerging 
them  in  the  hot  pools,  or  again  by  allowing  the  water  to  run  down  an 
inclined  plane  with  frequent  intervals  for  evaporation  and  concentration. 
The  vandals  who  delight  to  inscribe  their  names  in  public  places  have 
invaded  the  geyser  basins  in  large  numbers  and  left  their  addresses  upon 
the  geyserite  in  various  places.  It  is  interesting  to  note  how  quickly 
these  inscriptions  become  indelible  by  the  deposition  of  the  merest  film 
of  silica  upon  the  lead-pencil  marks,  and,  at  the  same  time,  how  slowly 
they  build  up.  Names  and  dates  known  to  be  6  and  8  years  old  remain 


BOWL  OF  GREAT  FOUNTAIN  GEYSER,  LOWER  GEYSER  BASIN. 

perfectly  legible,  and  still  retain  the  color  and  luster  of  the  graphite. 
That  there  is  some  increase  in  the  thickness  of  the  incrustation  is  evident, 
although  it  grows  with  incredible  slowness.  Mr.  Weed  tells  me  that  he 
has  been  able,  in  at  least  one  instance,  to  chip  off  this  siliceous  film  and 
reproduce  the  writing  with  all  its  original  distinctness,  showing  conclu- 
sively that  a  slow  deposition  has  taken  place.  Pencil  inscriptions  upon 
the  siliceous  sinter  at  Rotomahana  Lake,  in  New  Zealand,  are  said  to  be 
legible  after  the  lapse  of  20  or  30  years.  It  is  easy  to  see  that  various 
ingenious  devices  might  be  planned  to  estimate-  the  rate  of  deposition, 
but  in  my  opinion  none  of  them  equal  a  close  study  of  the  conditions 
found  in  nature,  especially  where  investigations  of  this  kind  can  be 
watched  from  year  to  year.  All  observations  show  an  rxcrnlin^lv  slow 
building  up  of  the  geyserite  formation.  This  is  well  seen  in  the  repair 


i8 


GEOLOGICAL   HISTORY    OF   YELLOWSTONE   PARK. 


going  on  where  the  rims  surrounding  the  hot  pools  have  been  broken 
down,  and  where  it  might  be  supposed  that  the  building-up  process  was 
under  the  most  favorable  conditions;  yet,  in  a  number  of  instances,  I  can 
see  no  appreciable  change  in  three  or  four  years.  Revisiting  hot  springs 
in  out-of-the-way  places  after  several  years'  absence,  I  am  surprised  to  see 
that  objects  that  I  had  noted  carefully  at  the  time  remain  unchanged. 
Taking  the  entire  area  of  the  Upper  Geyser  Basin  covered  by  sinter,  I 
believe  that  the  development  of  the  deposit  does  not  exceed  one-thirtieth 
of  an  inch  a  year,  and  this  estimate  I  believe  to  be  much  nearer  the 
maximum  than  the  minimum  rate  of  growth.  Supposing  the  deposit 
around  Castle  Geyser  to  have  been  built  up  with  the  same  slowness  as 


CONE  OF  CASTLE  GEYSER,  UPPER  GEYSER  BASIN. 

observed  to-day,  and  assuming  it  to  grow  at  the  rate  given — one-thirtieth 
of  an  inch  a  year — it  would  require  over  25,000  years  to  reach  its  present 
development.  This  gives  us  a  great  antiquity  for  the  geyserite,  but  I 
believe  that  the  deposition  of  the  siliceous  sinter  in  the  park  has  been 
going  on  for  a  still  longer  period  of  time.  It  is  certain  that  the  decom- 
position of  the  rhyolite  of  the  plateau  dates  still  further  back. 

From  a  geological  point  of  view,  there  is  abundant  evidence  that  ther- 
mal energy  is  gradually  becoming  extinct.  Tourists  revisiting  the  park 
after  an  absence  of  two  or  three  years  occasionally  allude  to  the  springs 
and  geysers  as  being  less  active  -than  formerly  and  as  showing  indica- 
tions of  rapidly  dying  out.  It  is  true  that  slight  changes  are  constantly 
taking  place,  that  certain  springs  become  extinct  or  discharge  less  water, 


GEOLOGICAL    HISTORY    OF    YELLOWSTONE    I'AKK. 


but  this  action  is  fully  counterbalanced  by  increased  activity  in  other 
localities.  Close  examination  of  the  source  of  the  thermal  waters  fails 
to  detect  any  diminution  in  the  supply.  Moreover,  it  stands  to  reason 
that  if  the  flow  of  these  waters  dated — geologically  speaking — far  back 
into  the  past,  the  few  years  embraced  within  the  historical  records  of 
the  park  would  be  unable  to  indicate  any  perceptible  change  based  upon 
a  gradual  diminution  of  the  heat. 

The  number  of  geysers,  hot  springs,  mudpots,  and  paintpots  scat- 
tered over  the  park  exceeds  3,000,  and  if  to  these  be  added  the  fumaroles 
and  solfataras,  from  which  issue  in  the  aggregate  enormous  volumes  of 
steam  and  acid  and  sulphur  vapors,  the  number  of  active  vents  would 
in  all  probability  be  doubled.  Each  one  of  these  vents  is  a  center  of 
decomposition  of  the  acid  lavas.  The  following  list  comprises  the  prin- 
cipal geysers  known  in  the  Norris,  Lower,  and  Upper  Geyser  Basins. 

NORRIS  GEYSER  BASIN— 15.    ' 


Bathtub, 
Black  Growler, 
Constant, 
Echinus, 


Bead, 

Clepsystra, 

Cliff, 

Excelsior, 

Fountain, 


Fearless, 
Hurricane, 
Minute  Man, 
Monarch , 


New  Crater, 
Pearl, 
Pebble, 
Valentine, 


\\teran, 

Vixen, 

Whirligig. 


LOWER  GEYSER  BASIN — 17. 


Fitful, 
Flood, 
Great  Fountain, 

Kaleidoscope, 
Narcissus, 
Pink  Cone, 

White  Dome, 
Young  Hopeful. 

Jelly, 
Jet, 

Steady, 
Surprise, 

UPPER  GEYSER  BASIN — 42. 


Artemesia, 

Bee  Hive, 

Bijou, 

Brilliant, 

Bulger, 

Cascade, 

Castle, 

Catfish, 

Chimney, 

Churn, 

Comet, 

A  comparative  study  of  the  analyses  of  the  fresh  rhyolite,  the  various 
transition  products,  and  the  thermal  waters  points  clearly  to  the  fact 
that  the  solid  contents  of  these  waters  are  derived  for  the  most  part  from 
the  volcanic  rocks  of  the  plateau.  During  the  progress  of  tin  \\ork  of 
the  Geological  Survey  in  the  Yellowstone  Park  tin-re  have  been  collected 
from  many  of  the  more  important  localities  samples  of  the  waters,  which 
have  been  subjected  to  searching  chemical  analyses  in  the  laboratory  of 
the  survey,  by  Messrs.  F.  A.  Gooch  and  J.  E.  Whittle  11 


Cub  (Big), 

Lioness, 

Spanker, 

Cub  (Little), 

Mastiff, 

Splendid, 

Daisy, 

Mortar, 

Sponge, 

Economic, 

Oblong, 

Spouter, 

Fan, 

Old  Faithful, 

Sprinkler, 

Giant, 

Restless, 

Sprite, 

Giantess, 

Riverside, 

Tardy, 

Grand, 

Rocket, 

Triplets, 

Grotto, 

Sawmill, 

Turban. 

Jewel, 

Sentinel, 

Lion, 

Spasmodic, 

20  GEOLOGICAL,  HISTORY   OF   YELLOWSTONE   PARK.    * 

They  are  all  siliceous  alkaline  waters  holding  the  same  mineral  con- 
stituents, but  in  varying  qualities.  Silica  forms  the  principal  deposit, 
not  only  immediately  around  the  springs  but  over  the  entire  floor  of 
the  basins.  The  carbonates,  sulphates,  chlorides,  and  traces  of  other 
easily  soluble  salts  are  carried  off  in  the  waters.  Oxides  of  iron  and 
manganese  and  occasionally  some  calcite  occur  under  certain  conditions 
in  the  caldrons  of  the  hot  springs  or  immediately  around  their  vents. 
Concentrations  from  large  quantites  of  these  waters  fail  to  show  the 
presence  of  even  a  trace  of  copper,  silver,  tin,  or  other  metal.  Nearly 
all  the  waters  carry  arsenic,  the  amount  present,  according  to  Messrs. 
Gooch  and  Whitfield,  varying  from  0.02  to  0.25  per  cent  of  the  mineral 
matter  in  solution. 

Among  the  incrustations  found  at  several  of  the  hot  springs  and  geysers 
is  a  leek-green  amorphous  mineral,  which  proves  on  investigation  to  be 
scorodite,  a  hydrous  arseniate  of  iron.  The  best  occurrence  observed  is 
at  Josephs  Coat  Springs,  on  the  east  side  of  the  Grand  Canyon  of  the 
Yellowstone,  where  it  occurs  as  a  coating  upon  the  siliceous  sinter  lining 
the  caldron  of  a  boiling  spring.  Analysis  shows  a  nearly  pure  scoro- 
dite, agreeing  closely  with  the  theoretical  composition: 

Ferric  oxide 34-94 

Arsenic  acid 48.  79 

Water 16.  27 

TOO.  OO 

Alteration  of  the  scorodite  into  limonite  takes  place  readily,  which  in 
turn  undergoes  disintegration  by  the  wearing  of  the  water,  and  is  mechani- 
cally carried  away.  So  far  as  I  know,  this  is  the  only  occurrence  where 
scorodite  has  been  recognized  as  deposited  from  the  waters  of  thermal 
springs.  Although  pure  scorodite  is  only  sparingly  preserved  at  a  few 
localities  in  the  Yellowstone  Park,  it  is  easily  recognized  by  its  charac- 
teristic green  color,  in  strong  contrast  with  the  white  geyserite  and  yellow 
and  red  oxides  of  iron.  After  a  little  practice  the  mineral  green  of  scoro- 
dite is  not  easily  mistaken  for  the  vegetable  green  of  the  algeous  growths. 
The  latter  is  associated  everywhere  with  the  hot  waters,  while  the  former, 
a  rare  mineral,  is  obtained  only  in  small  quantities  after  diligent  search. 
In  America  traces  of  arsenic  have  been  reported  from  several  springs  in 
Virginia,  and  quite  recently  sodium  arseniate  has  been  detected  in  the 
hot  springs  of  Ashe  County,  N.  C.  Arsenical  waters  of  sufficient  strength 
to  be  beneficial  for  remedial  purposes  and  not  otherwise  deleterious  are 
of  rare  occurrence.  In  France  the  curative  properties  of  arsenical  waters 
have  been  long  recognized,  and  the  famous  sanitarium  of  La  Bourboule, 
in  the  volcanic  district  of  the  Auvergne,  has  achieved  a  wide  reputation 
for  the  efficacy  of  its  waters  in  certain  forms  of  nervous  diseases.  Hy- 
geia  Springs  carries  0.3  of  a  grain  of  sodium  arseniate  to  the  gallon.  The 
Yellowstone  Park  waters,  while  they  carry  somewhat  less  arsenic  than 
those  of  La  Bourboule,  greatly  exceed  the  latter  in  their  enormous 


GEOLOGICAL  HISTORY  OF  YELLOWSTONE  PARK.  21 

overflow.  .  It  is  stated  that  the  entire  discharge  from  the  springs  of  La 
Bourboule  amounts  to  1,500  gallons  per  minute.  The  amount  of  hot 
water  brought  to  the  surface  by  the  hot  springs  throughout  the  park  is  by 
no  means  easily  determined,  although  during  the  progress  of  investigations 
I  hope  to  make  an  approximate  estimate.  According  to  the  most  accu- 
rate measurements  which  could  be  made,  the  discharge  from  the  caldron 
of  the  Excelsior  Geyser  amounted  to  4,400  gallons  of  boiling  water  per 
minute.  The  sample  of  the  Excelsior  Geyser  water  collected  August 
25,  1884,  yielded  0.19  grain  of  sodium  arsenate  to  the  gallon.  It  is 
impossible  to  say  as  yet  what  curative  pioperties  these  park  waters  may 
possess  in  alleviating  the  ills  of  mankind.  Nothing  but  an  extended 
experience  under  proper  medical  supervision  can  determine. 

Changes  modifying  the  surface  features  of  the  park  in  recent  times  are 
mainly  those  resulting  from  the  filling  up  with  detrital  matenal  of  the 
valleys  and  depressions  worn  out  by  glacial  ice,  and  those  produced  by 
the  prevailing  climatic  conditions.  Between  the  park  country  and  what 
is  known  as  the  arid  regions  of  the  West  there  is  the  greatest  possible  con- 
trast. Across  the  Central  Plateau  and  the  Absaroka  Range  the  country 
presents  a  continuous  mountain  mass  75  miles  in  width,  with  an  average 
elevation  unsurpassed  by  any  area  of  equal  extent  in  the  northern  Rocky 
Mountains.  It  is  exceptionally  situated  to  collect  the  moisture-laden 
clouds,  which  coming  from  the  southwest  precipitate  immense  quantities 
of  snow  and  rain  upon  the  cooled  tableland  and  neighboring  mountains. 
The  climate  in  many  respects  is  quite  unlike  that  found  in  the  adjacent 
country,  as  is  shown  by  the  meteorological  records,  the  amount  of  snow 
and  rainfall  being  higher,  and  the  mean  annual  temperature  lower. 
Rainstorms  occur  frequently  throughout  the  summer,  while  snow  is  quite 
likely  to  fall  any  time  between  September  and  May.  Protected  by  the 
forests  the  deep  snows  of  winter  lie  upon  the  plateau  well  into  midsum- 
mer, while  at  still  higher  altitudes,  in  sheltered  places,  it  remains  through- 
out the  year.  By  its  topographical  structure  the  park  is  designed  by 
nature  as  a  reservoir  for  receiving,  storing,  and  distributing  an  excep- 
tional water  supply,  not  exceded  by  any  area  near  the  headwaters  of  the 
great  continental  rivers.  The  Continental  Divide,  separating  the  waters 
of  the  Atlantic  from  those  of  the  Pacific,  crosses  the  park  plateau  from 
southeast  to  northwest.  On  both  sides  of  this  divide  lie  several  large 
bodies  of  water,  which  form  so  marked  a  feature  in  the  scenery  of  the 
plateau  that  the  region  has  been  designated  the  lake  country  of  the  park. 
Yellowstone  Lake,  the  largest  lake  in  North  America  at  this  altitude 
(7,740  feet)  and  one  of  the  largest  in  the  world  at  so  high  an  elevation 
above  sea  level,  presents  a  superficial  area  of  139  square  miles,  and  a 
shore  line  of  nearly  100  miles.  From  measurements  made  near  the 
outlet  of  the  lake  in  September,  1886,  the  driest  period  of  the  year,  the 
discharge  was  found  to  be  i  ,525  cubic  feet  per  second,  or  about  34,000,000 
imperial  gallons  per  hour. 


PUBLICATIONS  ON  YELLOWSTONE  NATIONAL  PARK. 

DISTRIBUTED   FREE    BY   THE    NATIONAL  PARK  SERVICE. 

The  following  publication  may  be  obtained  free  on  written  application 
to  the  Director  of  the  National  Park  Service: 

Rules  and  Regulations,  Yellowstone  National  Park  (issued  yearly).  This  pamphlet 
contains  general  information  of  interest  to  the  tourist. 

SOLD   BY  THE  SUPERINTENDENT   OF   DOCUMENTS. 

The  following  publications  may  be  obtained  from  the  Superintendent 
of  Documents,  Government  Printing  Office,  Washington,  D.  C.,  at  the 
prices  given.  Remittances  should  be  made  by  money  order  or  in 
cash: 

National  Parks  Portfolio,  by  Robert  Sterling  Yard.  260  pages,  including  270  illus- 
trations. Pamphlet  edition,  loose  in  flexible  cover,  35  cents;  book  edition,  con- 
taining same  material  securely  bound  in  cloth,  55  cents. 

Contains  nine  sections,  each  descriptive  of  a  national  park  and  one  larger  section  devoted  to 
other  national  parks  and  monuments. 

Geological  History  of  Yellowstone  National  Park,  by  Arnold  Hague,  22  pages, 
including  10  illustrations,  10  cents.  (This  publication.) 

This  pamphlet  contains  a  general  resume  of  the  geologic  forces  that  have  been  active  in   the 
Yellowstone  National  Park. 

Geysers,  by  Walter  Harvey  Weed,  32  pages,  including  23  illustrations,  10  cents. 

In  this  pamphlet  is  a  description  of  the  forces  which  have  produced  the  geysers,  and  the  geysers 
of  the  Yellowstone  are  compared  with  those  in  Iceland  and  New  Zealand. 

Fossil  Forests  of  the  Yellowstone  National  Park,  by  F.  H.  Knowlton,  32  pages,  includ- 
ing 15  illustrations,  10  cents. 

This  pamphlet  contains  descriptions  of  the  fossil  forests  of  the  Yellowstone  National  Park  and 
an  account  of  their  origin. 

MAP. 

A  topographic  map  of  the  park  may  be  purchased  from  the  Director 
of  the  Geological  Survey,  Washington,  D.  C.,  at  the  price  given.  Remit- 
tances should  be  made  by  cash  or  money  order. 

Map  of  Yellowstone  National  Park,  size  28^  by  32  inches;  scale,  2  miles  to  the 
inch.  Price,  25  cents. 

The  roads,  trails,  and  names  are  put  in  black,  the  streams  and  lakes  in  blue,  and  the  relief  is 
indicated  by  brown  contour  lines. 


O 


